Are benign cellular changes on a Papanicolaou smear really benign? A prospective cohort study.

OBJECTIVES: To determine the underlying prevalence of cervical intraepithelial neoplasia (CIN) in women with benign cellular changes on a Papanicolaou smear, and to evaluate follow-up strategies to identify women at high risk for serious underlying pathology. METHODS: Nonpregnant women aged 18 to 75 years with benign cellular changes on a Papanicolaou smear were recruited from primary care clinics of an urban teaching hospital. The subjects (N = 132) were tested at baseline for the presence of human papillomavirus using the polymerase chain reaction technique, and underwent repeated cervicovaginal smears at 3, 6, and 9 months. At 12 months colposcopy was performed. The main study outcome was the proportion of subjects with CIN as determined by colposcopic biopsy specimens. We determined the sensitivity, specificity, and predictive values of historical risk factor information, human papillomavirus testing, and repeated cervicovaginal smears for the detection of CIN. RESULTS: Cervical intraepithelial neoplasia was found in 30 of 132 women, of whom 27 (20%) had low-grade CIN (CIN I) and 3 (2%) had high-grade CIN (CIN II). Underlying CIN was significantly more common in women younger than 35 years or who had a history of Trichomonas infection or venereal warts, a positive human papillomavirus test result, or abnormal follow-up smears. However, no follow-up strategy combined high sensitivity with a low referral rate for colposcopy. CONCLUSIONS: The prevalence of underlying high-grade CIN in women with benign cellular changes is low. However, further prospective studies in other settings are needed before routine follow-up can unequivocally be recommended.